Joining Device and Joining Method

ABSTRACT

A joining device and method for laser-based joining of two components includes a first laser radiation source, a first radiation guide connected to the first radiation source to couple first laser radiation into the first radiation guide, a second laser radiation source, at least one second radiation guide connected to the second radiation source to couple second laser radiation into the second radiation guide, and a focusing device coupled to the laser radiations and focusing them at a distance from each other into a joining zone of the components. To reduce installation effort, the focusing device focuses the first and second laser radiations through a common beam path and a coupling device is connected on its input side to the first and second radiation guides and on its output side to the focusing device. The coupling device couples the first and second laser radiations into the common beam path.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuing application, under 35 U.S.C. § 120, of copendinginternational application No. PCT/EP2016/055944, filed Mar. 18, 2016,which designated the United States and was not published in English;this application also claims the priority, under 35 U.S.C. § 119, ofEuropean patent application No. 10 2015 207 279.7, filed Apr. 22, 2015;the prior applications are herewith incorporated by reference in theirentirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable

FIELD OF THE INVENTION

The present systems, apparatuses, and methods lie in the field ofjoining components. The present disclosure relates to a joining deviceand joining method utilizing laser radiation.

BACKGROUND OF THE INVENTION

A joining device and a joining method of the type mentioned above areknown, for example, from German Published, Non-Prosecuted PatentApplication DE 10 2006 038 422 A1. According to this document, the laserradiation of a first laser radiation source is used to effect materialbonding of two components in a joining zone formed by the latter. Thelaser radiation of a second laser radiation source is used to effectpreheating of the two components as a joining pretreatment in thejoining zone upstream to or preceding a joining direction of the laserradiation of the first laser radiation source. For this purpose, thefirst and second laser radiations emitted by separate laser radiationsources are focused into the joining zone by respective focusing devicesand optical systems necessitating an increased installation effort.

Thus, a need exists to overcome the problems with the prior art systems,designs, and processes as discussed above.

SUMMARY OF THE INVENTION

The systems, apparatuses, and methods described provide a joining deviceand joining method that overcome the hereinafore-mentioned disadvantagesof the heretofore-known devices and methods of this general type andthat provide such features with a reduction in the installation effort.

A joining device is provided for the laser radiation-based joining of atleast two components. The joining device comprises a first laserradiation source having a predetermined power configuration, a firstradiation guide, a second laser radiation source having a predeterminedpower configuration, at least one second radiation guide and focusingdevice.

The first radiation guide is connected to the first laser radiationsource in order to couple first radiation emitted from the first laserradiation source into the first radiation guide. The at least one secondradiation guide is connected to the second laser radiation source tocouple second laser radiation emitted from the second laser radiationsource into the at least one second radiation guide. The focusing deviceis coupled to the first and second radiation guides (preferably torespective radiation outlets thereof) and are configured to focus thefirst laser radiation and the second laser radiation at a distance fromeach into a joining zone of the two components.

The joining device is characterized in that the focusing device isconfigured to focus the first and the second laser radiation through acommon beam path, and in that the coupling device is provided and isconnected on the input side to the first and second radiation guides(preferably with the respective radiation outlets) and is connected onthe output side to the focusing device and is disposed to couple thefirst and the second laser radiation into the common beam path of thefocusing device.

Since the first and the second laser radiation can be focused through acommon beam path, there is no need to provide a separate beam path forfocusing for each of the two laser radiations and, thus, theinstallation effort for the joining device is reduced.

In an exemplary embodiment, the focusing device comprises a singleoptical system for focusing the first and second laser radiations. Theoptical system defines a single beam path, by which the first and secondlaser radiations can be jointly guided and can be focused into thejoining zone of the two components with multiple spaced-apart foci.

According to an exemplary embodiment, at least one further secondradiation guide is provided that is connected to the second laserradiation source to couple the second laser radiation into the at leastone further second radiation guide. In this way, the second laserradiation can advantageously be distributed to two working points in thejoining zone.

According to a further exemplary embodiment, the coupling devicecomprises a multi-core fiber with fiber cores, which, in particular,extend parallel to one another and the number of which corresponds tothe sum of first and second radiation guides, for guiding radiation. Thefiber cores, on one hand, are coupled respectively to one of respectiveradiation outlets of the first and second radiation guides and, on theother hand, are coupled respectively to the focusing device. In otherwords, in the multi-core fiber, the first and second radiation guides(optical fibers) are coupled in a common optical fiber cable (themulti-core fiber), which, in turn, is coupled to the focusing device. Asan alternative to the optical fiber cable or the multi-core fiber, acorresponding fiber coupler can also be provided, which makes itpossible, like the multi-core fiber, to image multiple foci over asingle beam path or with a single optical system.

According to yet another exemplary embodiment, the power configurationof the first laser radiation source differs from the power configurationof the second laser radiation source. In an exemplary embodiment, alaser beam power of the first laser radiation source is greater than alaser beam power of the second laser radiation source. By virtue ofthese differing power configurations of the two laser radiation sources,these laser radiation sources can be advantageously used for differenttasks in a joining process using the joining device.

Thus, the power configuration of the first laser radiation source is, inan exemplary embodiment, defined to effect a material bonding of the twocomponents with the focused first laser radiation by heat input. On theother hand, the power configuration of the second laser radiation sourceis defined to effect surface pretreatment at at least one of the twocomponents in the joining zone as a joining pretreatment with thefocused second laser radiation. In particular, the power configurationof the second laser radiation source is defined to effect ablationand/or melting of a coating on at least one of the two components in thejoining zone as a joining pretreatment with the focused second laserradiation. The power configuration of the second laser radiation sourceis defined to effect the joining pretreatment at both componentssimultaneously with the focused second laser radiation.

In this way, the laser-joining of coated components, such as sheetmetal, in particular hot-dip galvanized components, can beadvantageously made more reliable. In the case of conventionallaser-based joining devices, characteristic defects such as splashes,pores, attachment defects, or a rough weld surface could be observedduring the joining of coated components. Particularly in laser solderingof hot-dip galvanized components, a narrowing of the process window and,for example, a wavy edge connection of the soldering seam of the joiningzone were observed. The hitherto-missing possibility of producing laserbeam joining connections in an esthetically pleasing quality that, forexample, is suitable for external parts of motor vehicles, posed anobstacle to the use of hot-dip galvanized components (such as sheetmetal) for example in the exterior of motor vehicles.

The joining device, in which an irradiation of the component surfacewith the second laser radiation for changing the surface properties ofthe components can be carried out in addition to the actual joiningprocess with material bonding of the components based on the first laserradiation, can advantageously solve the problems existing in laserjoining of coated components.

With the joining device, melting and/or selective ablating of thecoating (in particular, of a zinc layer surface) of the components inthe area of the joining zone is made possible with the second laserradiation. Advantageously, the second laser radiation is focused intothe joining zone such that this pretreatment takes place inline anddirectly preceding the actual joining process with the first laserradiation, whereby the esthetically pleasing quality of the resultantjoining seam can be increased.

In addition, as a result of the heat input into the components precedingthe first laser radiation, a higher filling volume of solder and agreater bonding length of the solder to the components are achieved, inparticular, during laser soldering. Finally, the sensitivity of alaser-based joining process towards disturbance variables such as, forexample, fluctuations in the laser power or a component oiling isgenerally reduced, enabling reliable laser-based joining of hot-dipgalvanized or otherwise coated components.

There is also provided a joining method for laser radiation joining atleast two components. In an exemplary embodiment, the joining process isimplemented or executed using a joining device according to one,several, or all of the exemplary embodiments described herein in anyconceivable combination. In order to avoid repetitions, it is statedhere that the advantages and variations shown above for the joiningdevice apply to the joining method.

The joining process comprises the steps of: arranging the two componentsso as to define a joining zone for joining them together; focusing afirst laser radiation emitted from a first laser radiation source in alaser spot into the joining zone of the components so that a materialbonding of the two components is achieved in the area of the laser spotof the first laser radiation by heat input; focusing a second laserradiation emitted from a second laser radiation source in at least onelaser spot into the joining zone of the components preceding the laserspot of the first laser radiation in a joining direction, so that ajoining pretreatment is performed on at least one of the two componentsin the joining zone (FZ) in the area of the at least one laser spot. Thejoining method is characterized in that the first laser radiation andthe second laser radiation are focused into the joining zone through acommon beam path.

According to an exemplary embodiment, a surface pretreatment is carriedout on the at least one of the two components in the joining zone by theat least one laser spot of the second laser radiation as joiningpretreatment. In particular, ablation and/or melting of a coating on atleast one of the two components in the joining zone is performed assurface pretreatment by the at least one laser spot of the second laserradiation.

According to a further exemplary embodiment, the joining methodcomprises a soldering or welding process that enables the laser-joiningof hot-dip galvanized (and otherwise coated materials) by implementing aselective irradiation of the joining zone directly preceding the joiningprocess by utilizing a multi-core fiber, in particular, a three-corefiber. The multi-core fiber containing two, three, or more fiber coresallows the coupling of multiple optical fibers in an optical fibercable. This makes it possible to image the laser beams originating frommultiple laser radiation sources using a single optical system and,thus, to integrate the joining pretreatment, in particular, the ablationand/or melting of the zinc layer, into the soldering or welding process.Because only a single optical system is necessary for both laserradiations, conventional optical systems and systems can still be usedfollowing modification according to the exemplary embodiments. Becausethe surface pretreatment is done inline, no additional workstation isrequired.

In particular, a multi-core fiber with, for example, three fiber coresserves for guiding multiple (e.g., three) laser beams, which are inputinto a commercially available optical system by the multi-core fiber.This allows performance of the process adaptation, e.g., for hot-dipgalvanized sheet metal, while still using an existing soldering opticalsystem. Multiple laser spots, such as, in particular, three laser spots,from different laser radiation sources are imaged on the components tobe joined.

Thus, for example, a trifocal soldering can be realized by combining aninline upstream surface pretreatment and a downstream soldering.Advantageously, the second laser radiation used for surfacepretreatment, in particular, for ablation and/or melting of a coating ofthe components, can be guided on both sides on a solder wire onto thesurfaces of the components in the joining zone. The first laserradiation used for material bonding or soldering is subsequently fed tothe second laser radiation downstream of the joining zone.

In an exemplary embodiment, a continuously emitting first laserradiation source is used for the material bonding or soldering. For thesurface pretreatment or the change in the properties of the surfaces ofthe components, both a pulsed and a continuously emitting second laserradiation source can be used.

The invention also explicitly encompasses such embodiments, which arenot given by feature combinations from explicit back reference of theclaims, whereby the disclosed features of the invention can bearbitrarily combined with one another, insofar as this is technicallyuseful.

With the foregoing and other objects in view, there is provided, ajoining device for laser radiation-based joining of at least twocomponents at a joining zone comprises a first laser radiation sourcehaving a predetermined power configuration and configured to emit firstlaser radiation, a first radiation guide connected to the first laserradiation source to couple the first laser radiation emitted from thefirst laser radiation source into the first radiation guide, a secondlaser radiation source having a predetermined power configuration andconfigured to emit second laser radiation, at least one second radiationguide connected to the second laser radiation source to couple thesecond laser radiation emitted from the second laser radiation sourceinto the at least one second radiation guide, a focusing device coupledto the first radiation guide and to the at least one second radiationguide and configured to focus the first and second laser radiations at adistance from each other into the joining zone of the at least twocomponents and to focus the first and second laser radiations through acommon beam path, and a coupling device. The coupling device has aninput side and an output side, is connected on the input side to thefirst radiation guide and to the at least one second radiation guide, isconnected on the output side to the focusing device, and is configuredto couple the first and second laser radiations into the common beampath of the focusing device.

In accordance with another feature, the at least one second radiationguide is at least two second radiation guides each connected to thesecond laser radiation source to couple the second laser radiationemitted from the second laser radiation source into each of the at leasttwo second radiation guides.

In accordance with a further feature, the first radiation guide has afirst radiation outlet, the at least one second radiation guide has atleast one second radiation outlet, the coupling device has a multi-corefiber for guiding radiation and having a number of fiber corescorresponding to a sum of a number of the first radiation guide and theat least one second radiation guide, and the fiber cores arerespectively coupled to one of the first radiation outlet and the atleast one second radiation outlet and the focusing device.

In accordance with an added feature, the first radiation guide has afirst radiation outlet, the at least one second radiation guide has atleast one second radiation outlet, the coupling device has a multi-corefiber for guiding radiation and having a number of fiber corescorresponding to a sum of a number of the first radiation guide and theat least one second radiation guide, and the fiber cores each haveopposing ends one of the opposing ends coupled to one of the firstradiation outlet and the at least one second radiation outlet andanother of the opposing ends coupled to the focusing device.

In accordance with an additional feature, the first radiation guide hasa first radiation outlet, the at least two second radiation guidescomprise a first second radiation outlet and a second second radiationoutlet, the coupling device has a multi-core fiber for guiding radiationand having a number of fiber cores corresponding to a sum of a number ofthe first radiation guide and the at least two second radiation guides,and the fiber cores are respectively coupled to one of the firstradiation outlet, the first second radiation outlet, and the secondsecond radiation outlet, and to the focusing device.

In accordance with yet another feature, the first radiation guide has afirst radiation outlet, the at least two second radiation guidescomprise a first second radiation outlet and a second second radiationoutlet, the coupling device has a multi-core fiber for guiding radiationand having a number of fiber cores corresponding to a sum of a number ofthe first radiation guide and the at least two second radiation guides,and the fiber cores each have opposing ends one of the opposing endscoupled to one of the first radiation outlet, the first second radiationoutlet, and the second second radiation outlet, and another of theopposing ends coupled to the focusing device.

In accordance with yet a further feature, the power configuration of thefirst laser radiation source differs from the power configuration of thesecond laser radiation source.

In accordance with yet an added feature, the power configuration of thefirst laser radiation source is defined to effect a material bonding ofthe two components with the focused first laser radiation emitted by thefocusing device.

In accordance with yet an additional feature, the power configuration ofthe second laser radiation source is defined to effect, with the focusedsecond laser radiation emitted by the focusing device, surfacepretreatment at at least one of the two components in the joining zoneas a joining pretreatment.

In accordance with again another feature, at least one of the twocomponents comprises a coating in the joining zone and the powerconfiguration of the second laser radiation source is defined to effect,with the focused second laser radiation emitted by the focusing device,at least one of ablation and melting of the coating on at least one ofthe two components in the joining zone as a joining pretreatment.

With the objects in view, there is also provided a method for joining atleast two components by laser radiation comprising the steps ofdisposing the two components with respect to one another to define ajoining zone for joining the two components together, focusing a firstlaser radiation emitted from a first laser radiation source in a laserspot into the joining zone of the two components so that a materialbonding of the two components is achieved in an area of the laser spotof the first laser radiation by heat input, and focusing a second laserradiation emitted from a second laser radiation source in at least onelaser spot into the joining zone of the two components upstream of thelaser spot of the first laser radiation in a joining direction to effecta joining pretreatment on at least one of the two components in thejoining zone in an area of the at least one laser spot, the first laserradiation and the second laser radiation being focused into the joiningzone through a common beam path.

In accordance with again a further mode, a surface pretreatment isperformed as the joining pretreatment on the at least one of the twocomponents in the joining zone by the at least one laser spot of thesecond laser radiation.

In accordance with a concomitant mode, at least one of the twocomponents comprises a coating in the joining zone, and at least one ofablation and melting of the coating is performed on the at least one ofthe two components in the joining zone as the surface pretreatment bythe at least one laser spot of the second laser radiation.

Although the systems, apparatuses, and methods are illustrated anddescribed herein as embodied in a joining device and joining method, itis, nevertheless, not intended to be limited to the details shownbecause various modifications and structural changes may be made thereinwithout departing from the spirit of the invention and within the scopeand range of equivalents of the claims. Additionally, well-knownelements of exemplary embodiments will not be described in detail orwill be omitted so as not to obscure the relevant details of thesystems, apparatuses, and methods.

Additional advantages and other features characteristic of the systems,apparatuses, and methods will be set forth in the detailed descriptionthat follows and may be apparent from the detailed description or may belearned by practice of exemplary embodiments. Still other advantages ofthe systems, apparatuses, and methods may be realized by any of theinstrumentalities, methods, or combinations particularly pointed out inthe claims.

Other features that are considered as characteristic for the systems,apparatuses, and methods are set forth in the appended claims. Asrequired, detailed embodiments of the systems, apparatuses, and methodsare disclosed herein; however, it is to be understood that the disclosedembodiments are merely exemplary of the systems, apparatuses, andmethods, which can be embodied in various forms. Therefore, specificstructural and functional details disclosed herein are not to beinterpreted as limiting, but merely as a basis for the claims and as arepresentative basis for teaching one of ordinary skill in the art tovariously employ the systems, apparatuses, and methods in virtually anyappropriately detailed structure. Further, the terms and phrases usedherein are not intended to be limiting; but rather, to provide anunderstandable description of the systems, apparatuses, and methods.While the specification concludes with claims defining the systems,apparatuses, and methods of the invention that are regarded as novel, itis believed that the systems, apparatuses, and methods will be betterunderstood from a consideration of the following description inconjunction with the drawing figures, in which like reference numeralsare carried forward.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying figures, where like reference numerals refer toidentical or functionally similar elements throughout the separateviews, which are not true to scale, and which, together with thedetailed description below, are incorporated in and form part of thespecification, serve to illustrate further various embodiments and toexplain various principles and advantages all in accordance with thesystems, apparatuses, and methods. Advantages of embodiments of thesystems, apparatuses, and methods will be apparent from the followingdetailed description of the exemplary embodiments thereof, whichdescription should be considered in conjunction with the accompanyingdrawings in which:

FIG. 1 is a schematic side elevational view of an exemplary embodimentof a joining device;

FIG. 2 is a schematic plan view of a focusing device of the joiningdevice of FIG. 1; and

FIG. 3 is a fragmentary, perspective view of a joining zone of twocomponents irradiated with the joining device of FIG. 1.

DETAILED DESCRIPTION OF THE EMBODIMENTS

As required, detailed embodiments of the systems, apparatuses, andmethods are disclosed herein; however, it is to be understood that thedisclosed embodiments are merely exemplary of the systems, apparatuses,and methods, which can be embodied in various forms. Therefore, specificstructural and functional details disclosed herein are not to beinterpreted as limiting, but merely as a basis for the claims and as arepresentative basis for teaching one skilled in the art to variouslyemploy the systems, apparatuses, and methods in virtually anyappropriately detailed structure. Further, the terms and phrases usedherein are not intended to be limiting; but rather, to provide anunderstandable description of the systems, apparatuses, and methods.While the specification concludes with claims defining the features ofthe systems, apparatuses, and methods that are regarded as novel, it isbelieved that the systems, apparatuses, and methods will be betterunderstood from a consideration of the following description inconjunction with the drawing figures, in which like reference numeralsare carried forward.

In the following detailed description, reference is made to theaccompanying drawings which form a part hereof, and in which are shownby way of illustration embodiments that may be practiced. It is to beunderstood that other embodiments may be utilized and structural orlogical changes may be made without departing from the scope. Therefore,the following detailed description is not to be taken in a limitingsense, and the scope of embodiments is defined by the appended claimsand their equivalents.

Alternate embodiments may be devised without departing from the spiritor the scope of the invention. Additionally, well-known elements ofexemplary embodiments of the systems, apparatuses, and methods will notbe described in detail or will be omitted so as not to obscure therelevant details of the systems, apparatuses, and methods.

Before the systems, apparatuses, and methods are disclosed anddescribed, it is to be understood that the terminology used herein isfor the purpose of describing particular embodiments only and is notintended to be limiting. The terms “comprises,” “comprising,” or anyother variation thereof are intended to cover a non-exclusive inclusion,such that a process, method, article, or apparatus that comprises a listof elements does not include only those elements but may include otherelements not expressly listed or inherent to such process, method,article, or apparatus. An element proceeded by “comprises . . . a” doesnot, without more constraints, preclude the existence of additionalidentical elements in the process, method, article, or apparatus thatcomprises the element. The terms “including” and/or “having,” as usedherein, are defined as comprising (i.e., open language). The terms “a”or “an”, as used herein, are defined as one or more than one. The term“plurality,” as used herein, is defined as two or more than two. Theterm “another,” as used herein, is defined as at least a second or more.The description may use the terms “embodiment” or “embodiments,” whichmay each refer to one or more of the same or different embodiments.

The terms “coupled” and “connected,” along with their derivatives, maybe used. It should be understood that these terms are not intended assynonyms for each other. Rather, in particular embodiments, “connected”may be used to indicate that two or more elements are in direct physicalor electrical contact with each other. “Coupled” may mean that two ormore elements are in direct physical or electrical contact (e.g.,directly coupled). However, “coupled” may also mean that two or moreelements are not in direct contact with each other, but yet stillcooperate or interact with each other (e.g., indirectly coupled).

For the purposes of the description, a phrase in the form “A/B” or inthe form “A and/or B” or in the form “at least one of A and B” means(A), (B), or (A and B), where A and B are variables indicating aparticular object or attribute. When used, this phrase is intended toand is hereby defined as a choice of A or B or both A and B, which issimilar to the phrase “and/or”. Where more than two variables arepresent in such a phrase, this phrase is hereby defined as includingonly one of the variables, any one of the variables, any combination ofany of the variables, and all of the variables, for example, a phrase inthe form “at least one of A, B, and C” means (A), (B), (C), (A and B),(A and C), (B and C), or (A, B and C).

Relational terms such as first and second, top and bottom, and the likemay be used solely to distinguish one entity or action from anotherentity or action without necessarily requiring or implying any actualsuch relationship or order between such entities or actions. Thedescription may use perspective-based descriptions such as up/down,back/front, top/bottom, and proximal/distal. Such descriptions aremerely used to facilitate the discussion and are not intended torestrict the application of disclosed embodiments. Various operationsmay be described as multiple discrete operations in turn, in a mannerthat may be helpful in understanding embodiments; however, the order ofdescription should not be construed to imply that these operations areorder dependent.

As used herein, the term “about” or “approximately” applies to allnumeric values, whether or not explicitly indicated. These termsgenerally refer to a range of numbers that one of skill in the art wouldconsider equivalent to the recited values (i.e., having the samefunction or result). In many instances these terms may include numbersthat are rounded to the nearest significant figure. As used herein, theterms “substantial” and “substantially” means, when comparing variousparts to one another, that the parts being compared are equal to or areso close enough in dimension that one skill in the art would considerthe same. Substantial and substantially, as used herein, are not limitedto a single dimension and specifically include a range of values forthose parts being compared. The range of values, both above and below(e.g., “+/−” or greater/lesser or larger/smaller), includes a variancethat one skilled in the art would know to be a reasonable tolerance forthe parts mentioned.

Herein various embodiments of the systems, apparatuses, and methods aredescribed. In many of the different embodiments, features are similar.Therefore, to avoid redundancy, repetitive description of these similarfeatures may not be made in some circumstances. It shall be understood,however, that description of a first-appearing feature applies to thelater described similar feature and each respective description,therefore, is to be incorporated therein without such repetition.

Described now are exemplary embodiments. Referring now to the figures ofthe drawings in detail and first, particularly to FIGS. 1 to 3, there isshown a first exemplary embodiment of a joining device 1 for the laserbeam-based joining of at least two components B1, B2 (see FIG. 3) and ajoining method using the joining device 1 according to exemplaryembodiments. According to an exemplary embodiment of the joining device1 described here, the joining device 1 is configured for the laserbeam-based soldering of the two components B1, B2.

As shown in FIG. 3, the two components B1, B2 are disposed with respectto one another so that they form a strip-shaped joining zone FZ forjoining the components B1, B2. In this case, the joining zone FZ can beformed, for example, of two blunt abutting boundary edges of the twocomponents B1, B2. In addition, the boundary edges of the two componentsB1, B2 in the joining zone FZ can define a fillet for forming a filletweld. In the present embodiment, each of the two components B1, B2 is anexterior part for a vehicle body, wherein the two components B1, B2 areall-round hot-dip galvanized for corrosion protection; a zinc coating isapplied to each component B1, B2 by hot-dip galvanizing.

As shown in FIGS. 1 to 3, the joining device 1 comprises a first laserradiation source 10, a first radiation guide 11, a second laserradiation source 20, a pair of second radiation guides 21, 25, couplingdevice 30, a focusing device 40, and additional material feeding device50 for feeding a solder wire 51 and an inert gas (not shown) into thejoining zone FZ.

The first radiation guide 11 is connected to the first laser radiationsource 10 to couple first laser radiation LS1 emitted from the firstlaser radiation source 10 into the first radiation guide 11. The twosecond radiation guides 21, 25 are respectively connected to the secondlaser radiation source 20 to couple second laser radiation LS2 emittedfrom the second laser radiation source 20 into each of the two secondradiation guides 21 25. The first and second radiation guides 11, 21, 25are formed, for example, as separate optical fibers.

The coupling device 30 is connected on an input side to respectiveradiation outlets (not separately indicated) of the first and secondradiation guides 11, 21, 25 and is connected on an output side to thefocusing device 40 to introduce the first and second laser radiationsLS1, LS2 into the focusing device 40.

The focusing device 40, which is coupled to the respective radiationoutlets of the first and second radiation guides 11, 21, 25 through thecoupling device 30, comprises an optical system (not separatelyindicated) for focusing the first and second laser radiations LS1, LS2.The optical system of the focusing device 40 defines a single beam path,by which the first and second laser radiations LS1, LS2 can be jointlyguided and thereby focused with multiple spaced-apart foci into thejoining zone FZ of the two components B1, B2.

The coupling device 30 has a multi-core fiber (not separately indicated)with fiber cores (not separately indicated), which extend parallel toone another and the number of which corresponds to the sum of first andsecond radiation guides 11, 21, 25, for guiding radiation. In otherwords, in the multi-core fiber, the first and second radiation guides11, 21, 25 (optical fibers) are coupled in a common optical fiber cable(the multi-core fiber). The fiber cores of the multi-core fiber, on onehand, are coupled respectively to one of the radiation outlets of thefirst and second radiation guides 11, 21, 25 and, on the other hand, arecoupled respectively to the focusing device 40. As a result, thecoupling device 30 is configured to couple the first and second laserradiations LS1, LS2 into a common beam path of the optical system of thefocusing device 40.

A predetermined power configuration of the first laser radiation source10 and a predetermined power configuration of the second laser radiationsource 20 are defined to be different from one another other. In theexemplary embodiment of the joining device 1 described here, a laserbeam power of the first laser radiation source 10 is greater than alaser beam power of the second laser radiation source 20.

More specifically, the power configuration of the first laser radiationsource 10 is defined to effect material bonding of the two componentsB1, B2 with the focused first laser radiation LS1 by heat input. Inother words, the first laser radiation source 10 functions as joiningradiation source, by which the solder wire 51 fed by the additionalmaterial feeding device 50 is melted when the two components B1, B2 arejoined together, and the boundary edges of the two components B1, B2located in the joining zone FZ are heated at least in the melting zoneof the solder wire 51 up to the soldering temperature.

The power configuration of the second laser radiation source 20 isdefined, however, to effect surface pretreatment with the focused secondlaser radiation LS2 at the two components B1, B2 in the joining zone FZas a joining pretreatment. In the exemplary embodiment of the joiningdevice 1 described here, the power configuration of the second laserradiation source 20 is defined to effect ablation and/or melting of thezinc coating applied respectively to the components B1, B2 by hot-dipgalvanizing in the joining zone FZ as surface pretreatment.

In the following text, a joining method using the joining device 1 forlaser radiation joining of the two components B1, B2 is described withreference to the above description of the structure of the joiningdevice 1.

According to the joining method, the two components are first disposedat a mounting location of the joining device 1 such that they define thestrip-shaped joining zone FZ for joining the components B1, B2, as shownin FIG. 3. Then, the additional material feeding device 50 for feedingthe solder wire 51 and the inert gas is placed at an angle to thejoining zone FZ.

In addition, the first and second laser radiation sources 10, 20 arealigned with the joining zone FZ and put into operation. The first laserradiation LS1 and the second laser radiation LS2 are focused into thejoining zone FZ through the common beam path of the optical system ofthe focusing device 40.

More specifically, the first laser radiation LS1 emitted from the firstlaser radiation source 10 is focused in a laser spot LS1′ (which has adiameter of about 3.2 mm, for example) in the middle of the width of thestrip-shaped joining zone FZ of components B1, B2, so that in the areaof the laser spot LS1′ of the first laser radiation LS1 material bondingof the two components B1, B2 is achieved by heat input. For thispurpose, the solder wire 51 fed by the additional material feedingdevice 50 is melted in the area of the laser spot LS1′ of the firstlaser radiation LS1 and the boundary edges of the two components B1, B2are heated up to the soldering temperature.

The second laser radiation LS2 emitted by the second laser radiationsource 20 is focused in two laser spots LS2′ at a distance from oneanother into the joining zone FZ of the components B1, B2, in a joiningdirection FR preceding or upstream of the laser spot LS1′ of the firstlaser radiation LS1 at a predetermined distance, in the region of thetwo laser spots LS2′ of the second laser radiation LS2, so that thesurface pretreatment as joining pretreatment is performed on the twocomponents B1, B2 in the area of the two laser spots LS2′ of the secondlaser radiation LS2 in the joining zone FZ. Within the scope of thesurface pretreatment, the zinc coating on the two components B1, B2 isablated in the joining zone FZ by the two laser spots LS2′ of the secondlaser radiation LS2, which have a diameter that is reduced in comparisonto the diameter of the downstream laser spot LS1′.

Thus, so to speak, a trifocal soldering is realized with the combinationof an inline upstream surface pretreatment and a downstream soldering.As shown in FIG. 3, the second laser radiation LS2 used for surfacepretreatment, in particular, for ablation and/or melting of the zinccoating, is guided on both sides of the solder wire 51 onto the surfacesof the components B1, B2 in the joining zone FZ. The first laserradiation LS1 used for material bonding, e.g., soldering, is fed to thejoining zone FZ downstream to the second laser radiation LS2.

A continuously emitting first laser radiation source 10 is used for thematerial bonding or soldering. Both a pulsed and a continuously emittingsecond laser radiation source 20 can be used for the surfacepretreatment or the change in the properties of the surfaces of thecomponents B1, B2.

The joining device and joining process allow for a more reliable laserjoining, in particular, laser soldering, of coated or hot-dip galvanizedcomponents (in particular, sheet metals). In conventional solutions, forexample, in laser soldering of hot-dip galvanized components, anarrowing of the process window and the formation of characteristicdefects, for example, a wavy edge connection of the soldering seam ofthe joining zone FZ were observed. The solution according to theexemplary embodiments, in which the wetting of the components B1, B2with the solder of the solder wire 51 is preceded by an irradiation ofthe component surface, makes it possible to change the surfaceproperties of the components B1, B2.

In particular, melting and/or selective ablating of the coating (inparticular, zinc coating surface) in the area of the joining zone FZ ismade possible by the exemplary embodiments herein. The inline joiningpretreatment, which directly precedes a joining process, increases theesthetically pleasing quality of the resulting joining seam. Inaddition, as a result of the heat introduced precedingly into thecomponents B1, B2, a higher filling volume of solder and a greaterbonding length of the solder on the components B1, B2 are also achievedduring soldering. Finally, the sensitivity of a laser-based joiningprocess towards disturbance variables such as, for example, fluctuationsin the laser power or a component oiling is reduced, enabling reliablelaser-based joining of hot-dip galvanized or otherwise coatedcomponents.

LIST OF REFERENCE NUMERALS

-   1 Joining device-   10 first laser radiation source-   11 first radiation guide-   20 second laser radiation source-   21 second radiation guide-   25 second radiation guide-   30 coupling device-   40 focusing device-   50 additional material feeding device-   51 solder wire-   B1 component-   B2 component-   FR joining direction-   FZ joining zone-   LS1 first laser radiation-   LS1′ laser spot-   LS2 second laser radiation-   LS2′ laser spot

It is noted that various individual features of the inventive processesand systems may be described only in one exemplary embodiment herein.The particular choice for description herein with regard to a singleexemplary embodiment is not to be taken as a limitation that theparticular feature is only applicable to the embodiment in which it isdescribed. All features described herein are equally applicable to,additive, or interchangeable with any or all of the other exemplaryembodiments described herein and in any combination or grouping orarrangement. In particular, use of a single reference numeral herein toillustrate, define, or describe a particular feature does not mean thatthe feature cannot be associated or equated to another feature inanother drawing figure or description. Further, where two or morereference numerals are used in the figures or in the drawings, thisshould not be construed as being limited to only those embodiments orfeatures, they are equally applicable to similar features or not areference numeral is used or another reference numeral is omitted.

The foregoing description and accompanying drawings illustrate theprinciples, exemplary embodiments, and modes of operation of thesystems, apparatuses, and methods. However, the systems, apparatuses,and methods should not be construed as being limited to the particularembodiments discussed above. Additional variations of the embodimentsdiscussed above will be appreciated by those skilled in the art and theabove-described embodiments should be regarded as illustrative ratherthan restrictive. Accordingly, it should be appreciated that variationsto those embodiments can be made by those skilled in the art withoutdeparting from the scope of the systems, apparatuses, and methods asdefined by the following claims.

What is claimed is:
 1. A joining device for laser radiation-basedjoining of at least two components at a joining zone, the joining devicecomprising: a first laser radiation source having a predetermined powerconfiguration and configured to emit first laser radiation; a firstradiation guide connected to the first laser radiation source to couplethe first laser radiation emitted from the first laser radiation sourceinto the first radiation guide; a second laser radiation source having apredetermined power configuration and configured to emit second laserradiation; at least one second radiation guide connected to the secondlaser radiation source to couple the second laser radiation emitted fromthe second laser radiation source into the at least one second radiationguide; a focusing device: coupled to the first radiation guide and tothe at least one second radiation guide; and configured to focus thefirst and second laser radiations at a distance from each other into thejoining zone of the at least two components and to focus the first andsecond laser radiations through a common beam path; and a couplingdevice: having an input side and an output side; connected on the inputside to: the first radiation guide; and the at least one secondradiation guide; connected on the output side to the focusing device;and configured to couple the first and second laser radiations into thecommon beam path of the focusing device.
 2. The joining device accordingto claim 1, wherein the at least one second radiation guide is at leasttwo second radiation guides each connected to the second laser radiationsource to couple the second laser radiation emitted from the secondlaser radiation source into each of the at least two second radiationguides.
 3. The joining device according to claim 1, wherein: the firstradiation guide has a first radiation outlet; the at least one secondradiation guide has at least one second radiation outlet; the couplingdevice has a multi-core fiber for guiding radiation and having a numberof fiber cores corresponding to a sum of a number of the first radiationguide and the at least one second radiation guide; and the fiber coresare respectively coupled to: one of the first radiation outlet and theat least one second radiation outlet; and the focusing device.
 4. Thejoining device according to claim 1, wherein: the first radiation guidehas a first radiation outlet; the at least one second radiation guidehas at least one second radiation outlet; the coupling device has amulti-core fiber for guiding radiation and having a number of fibercores corresponding to a sum of a number of the first radiation guideand the at least one second radiation guide; and the fiber cores eachhave opposing ends: one of the opposing ends coupled to one of the firstradiation outlet and the at least one second radiation outlet; andanother of the opposing ends coupled to the focusing device.
 5. Thejoining device according to claim 2, wherein: the first radiation guidehas a first radiation outlet; the at least two second radiation guidescomprise a first second radiation outlet and a second second radiationoutlet; the coupling device has a multi-core fiber for guiding radiationand having a number of fiber cores corresponding to a sum of a number ofthe first radiation guide and the at least two second radiation guides;and the fiber cores are respectively coupled to: one of: the firstradiation outlet; the first second radiation outlet; and the secondsecond radiation outlet; and to the focusing device.
 6. The joiningdevice according to claim 2, wherein: the first radiation guide has afirst radiation outlet; the at least two second radiation guidescomprise a first second radiation outlet and a second second radiationoutlet; the coupling device has a multi-core fiber for guiding radiationand having a number of fiber cores corresponding to a sum of a number ofthe first radiation guide and the at least two second radiation guides;and the fiber cores each have opposing ends: one of the opposing endscoupled to one of: the first radiation outlet; the first secondradiation outlet; and the second second radiation outlet; and another ofthe opposing ends coupled to the focusing device.
 7. The joining deviceaccording to claim 1, wherein the power configuration of the first laserradiation source differs from the power configuration of the secondlaser radiation source.
 8. The joining device according to claim 1,wherein the power configuration of the first laser radiation source isdefined to effect a material bonding of the at least two components withthe focused first laser radiation emitted by the focusing device.
 9. Thejoining device according to claim 1, wherein the power configuration ofthe second laser radiation source is defined to effect, with the focusedsecond laser radiation emitted by the focusing device, surfacepretreatment at at least one of the at least two components in thejoining zone as a joining pretreatment.
 10. The joining device accordingto claim 1, wherein: at least one of the at least two componentscomprises a coating in the joining zone; and the power configuration ofthe second laser radiation source is defined to effect, with the focusedsecond laser radiation emitted by the focusing device, at least one ofablation and melting of the coating on at least one of the at least twocomponents in the joining zone as a joining pretreatment.
 11. A methodfor joining at least two components by laser radiation, which comprises:disposing the two components with respect to one another to define ajoining zone for joining the two components together; focusing a firstlaser radiation emitted from a first laser radiation source in a laserspot into the joining zone of the two components so that a materialbonding of the two components is achieved in an area of the laser spotof the first laser radiation by heat input; and focusing a second laserradiation emitted from a second laser radiation source in at least onelaser spot into the joining zone of the two components upstream of thelaser spot of the first laser radiation in a joining direction to effecta joining pretreatment on at least one of the two components in thejoining zone in an area of the at least one laser spot, the first laserradiation and the second laser radiation being focused into the joiningzone through a common beam path.
 12. The method according to claim 11,which further comprises performing a surface pretreatment as the joiningpretreatment on the at least one of the two components in the joiningzone by the at least one laser spot of the second laser radiation. 13.The method according to claim 12, wherein at least one of the twocomponents comprises a coating in the joining zone, and which furthercomprises performing at least one of ablation and melting of the coatingon the at least one of the two components in the joining zone as thesurface pretreatment by the at least one laser spot of the second laserradiation.